The overall objective of the proposed investigation is to express hepatitis B viral genes in E. coli to facilitate the identification and characterization of viral proteins in virus particles, infectious sera, and a human hepatoma. Specifically, studies will be performed to: 1) Apply and develop procedures to maximize eukaryotic gene expression in E. coli using the B-galactosidase regulatory signals for transcription and translation. 2) Compare the primary and higher order structure of defined viral proteins synthesized in E. coli to native viral proteins. The tryptic digests and antigenic determinants of the nucleocapsid protein (HBcAg) and surface antigen (HBsAg) will be examined. 3) Synthesize in E. coli large quantities of polypeptides which have not been characterized either antigenically or enzymatically but have been predicted by the DNA sequence of the HBV genome. 4) Using antisera generated to these undefined polypeptides, examine virus particles, infectious sera, and a human hepatoma cell line to determine if these antigens are present. 5) Insert and propagate in E. coli, HBV DNA from various patients. The location and identification of variability of endonuclease sites in HBV DNA isolated from different patients will serve two functions. First, this 'library' of HVB DNA's will allow increased flexibility for the manipulation of viral genes in order to accomplish their expression in E. coli. Second, the localization of regions of the DNA that remain unaltered may assist in the correlation of structure and function. The proposed research marks the initial stages of the long range program of my laboratory to study hepatitis B virus maturation using the expression and manipulation of viral genes in E. coli. An understanding of viral protein maturation is essential for the eventual characterization of what now appears to be a new class of viruses.